ML20236U861

Application for Amend to Licenses NPF-4 & NPF-7,revising EDG Section to Be Consistent W/Station Procedures Associated W/ Steady State Conditions & W Nuclear Safety Advisory Ltr,Nsal 93-022

ML20236U861
Person / Time
Site:	North Anna
Issue date:	07/28/1998
From:	Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20236U864	List: ML20236U861 ML20236U871
References
98-435, NUDOCS 9807310121
Download: ML20236U861 (11)

Text

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.O ViluilNI A El.ECTRIC ANI> POwen CONWANY RICitMOND, VHMilNE A U261

, July 28, 1998 U.S. Nuclear Regulatory Commission Serial No.98-435 Attention: Document Control Desk NL&OS/GSS/ETS R0 Washington, D.C. 20555 Docket Nos. 50-338 50-339 i License Nos. NPF-4  !

NPF-7  !

Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 PROPOSED TECHNICAL SPECIFICATION CHANGE EDG STEADY STATE FREQUENCY REQUIREMENTS Pursuant to 10 CFR 50.90, Virginia Electric and Power Company requests amendments, in the form of changes to the Technical Specifications and to Facility Operating License Numbers NPF-4 and NPF-7 for North Anna Power Station Units 1 and 2, respectively. The proposed changes will revise the EDG section to be consistent with station procedures associated with steady state conditions and Westinghouse Nuclear Safety Advisory Letter, NSAL 93-022. A discussion of the proposed Technical Specifications changes is provided in Attachment 1.

The proposed Technical Specifications changes have been reviewed and approved by j the Station Nuclear Safety and Operating Committee and the Management Safety Review Committee. It has been determined that the proposed Technical Specifications .

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changes do not involve an unreviewed safety question as defined in 10 CFR 50.59 or a significant hazards consideration as defined in 10 CFR 50.92. The proposed Technical l Specifications changes are provided as a mark-up in Attachment 2 and a typed version

! in Attachment 3. The basis for our determination that the changes do not involve a significant hazards consideration is provided in Attachment 4. [igyj y If you have any fudher questions, please contact us.

l Very truly yours, 1

James P. O'Hanlon Senior Vice President - Nuclear 9807310121 980728 PDR ADOCK 05000338 P PDR L

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• Attachments

1. Discussion of Changes

2. Mark-up of Technical Specifications Changt '

l 3. Proposed Technical Specifications Changes j 4. Significant Hazards Consideration Determination l

l Commitments made in this letter:

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1. There are no commitments in this letter i

cc: U.S. Nuclear Regulatory Commission l

Region ll Atlanta Federal Center 61 Forsyth Street, SW  !

Suite 23T85 Atlanta, Georgia 30303 i

i Mr. M. J. Morgan l NRC Senior Resident inspector North Anna Power Station Commissioner Department of Radiological Health l Room 104A 1500 East Main Street Richmond, VA 23219 1

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COMMONWEALTH OF VIRGINIA ) l

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COUNTY OF HENRICO ) 1 The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by J. P. O'Hanlon, who is Senior Vice President - Nuclear, of Virginia Electric and Power Company. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief.

Ac (nowledged before me thisO day of f ,19h .

My Commission Expires: Marcil 31, 2000.

00bt (04bh

/ Notary Public l

e (SEAL)

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Attachment 1 l

Discussion of Change 1

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l North Anna Power Station Units 1 and 2 Virginia Electric and Power Company i

1 Di curi:n cf Ch;nges i introduction l -

. Pursuant to 10 CFR 50.90, Virginia Electric and Power Company requests changes to

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l Technical Specifications Surveillance Requirements 4.8.1.1.2.a.4, 4.8.1.1.2.c,

4.8.1,1.2.d.2, 4.8.1.1.2.d.4.b, 4.8.1.1.2.d.5, 4.8.1.1.2.d.6.b, 4.8.1.1.2.d.11.b, and l 4.8.1.1.2.e for North Anna Power Station Units 1 and 2. The Technical Specifications

! sunmillance requirements currently require each Emergency Diesel Generator (EDG) to be l

l demonstrated OPERABLE by the performance of the specific Surveillance Requirements.

One significant pa t of demonstrating operability of the EDG requires verification that the l frequency is within a specified range. This requirement is currently reflected in the North  ;

Anna Technical Specifications as 60 i 1.2 Hz. Based upon a 1993 Westinghouse Nuclear l Safety Advisory Letter (NSAL 93-022), North Anna procedures were revised to reflect a 1 l

narrower EDG frequency range in 1995 of 60 i 0.5 Hz. The NSAL indicated that Westinghouse accident analyses assumed a steady state EDG frequency of 60 Hz, making no specific allowance for the effects on ESF pump performance at steady state frequency limits that are currently permitted by Technical Specifications.

Margin exists in the North Anna accident analyses to account for some level of frequency l variation from 60 Hz on the emergency bus supplied by the EDG, and i 0.5 Hz has been l evaluated by Engineering as acceptable.

l The proposed changes to the North Anna Units 1 and 2 Technical Specifications will not adversely affect the safe operation of the plant or result in an unreviewed safety question as defined by the criteria of 10 CFR 50.59.

Background

l Current Licensing Basis The original EDG testing requirements that verified the frequency were issued as part of amendment 83 dated August 28,1986 for North Anna Unit 1 and as part of the original operating licenses for Unit 2 dated August 21,1980. Unit 1 amendment 83 was part of the effort to make Unit 1 identical to the already approved Unit 2 Technical Specifications.

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Currsnt De ign B: sis e

The EDG supplies the emergency bus with electrical power within 10 seconds of receiving ,

an emergency start signal. With the emergency bus de-energized, the EDG output breaker will'close when the EDG output voltage reaches 95% of rated voltage. The frequency requirement of 60 0.5 Hz is based on the analyzed steady state limit for the EDG. The EDG supplies the electrical power for the required equipment to mitigate the consequences of design basis events. The steady state voltage and frecuency limits of 4160 420 volts and 60 i 0.5 Hz ensure that the ESF pumps will supply the minimum flow necessary to maintain the fuel within the required PCT limits.  ;

Safety Guide 9 is the primary licensing document for the North Anna Units and is considered the base document for licensing of the station. However, additional standards )

I and regulatory guides are used in part as references based on good engineering practice.

The guidance of IEEE308,1974, Section 4.3, Power Quality and Regulatory Guide 1.9, i Rev 1, Section C.5 (transient response to the disconnection of the largest single electrical load) were the technical reference sources considered in the evaluation for the frequency requirements for transient and staady state conditions and for making this change to the Technical Specification.

l Discussion

( During a review of the EDG System, Virginia Power's resolution of an issue involving EDG

- frequency range control stemming from a 1993 Westinghouse Nuclear Safety Advisory Letter (NSAL 93-022) was reviewed. The letter indicated that the Westinghouse accident analyses assumed a steady state EDG frequency of 60 HZ, making no specific allowance for the effects on ESF pump performance at steady state frequency limits that are currently permitted by Technical Specifications. The review determined that earlier engineering assessments were made which found that steady-state EDG operation at the limits permitted by the NAPS Technical Specifications could effect ECCS equipment  ;

performance so that it would not support accident analysis assumed values. These assessments and reanalysis further determined an acceptable range of EDG frequency,60 ,

0.5 Hz, within which accident analysis assumptions would be met. This range was Page 2 of 7

incorporated into station procedures. Thsrefore, a TS change is needed to reestablish TS control of EDG frequency at these new values.

Specific Changes The following Technical Specification changes applies to both Units 1 and 2:

1. Surveillance Requirement 4.8.1.1.2.a.4 requires each EDG to be demonstrated OPERABLE by verification that the EDG can start and gradually accelerate to synchronous speed (900 rpm). The EDG must maintain a generator voltage of 4160 420 volts and a frequency of 60 1.2 Hz. The proposed change will limit the steady state frequency range to 60 0.5 Hz and will eliminate the reference to the synchronous speed of 900 rpm.

2. Surveillance Requirement 4.8.1.1.2.c requires at least once per 184 days that each EDG will be demonstrated OPERABLE by starting and accelerating to 900 rpm in s 10 seconds. The EDG voltage and frequency limits for this start are 4160 420 volts and 60 1.2 Hz. The EDG is then required to be synchronized to the emergency bus, gradually loaded to an indicated 2500 to 2600 kw, and operated for at least 60 minutes.

The proposed change modifies the 10 seconds start requirements to achieve voltage and frequency of 2 3960 volts and 2 59.5 Hz. It also removes the statement of obtaining 900 rpm. The voltage requirement is based on the EDG output breaker close permissive (95% voltage). Furthermore, it establishes a steady state voltage and frequency c,f 4160 i 420 volts and 60 i 0.5 Hz.

3. Surveillance Requirement 4.8.1.1.2.d.2 requires each EDG to be demonstrated OPERABLE at least once every 18 months during shutdown by verification that the EDG can reject a load of 610 kW. The EDG is required to snaintain a generator voltage of 4160 420 volts and a frequency of 60 1.2 Hz during the transient. The proposed change will limit the steady state frequency range following the transient to 60 0.5 Hz.

The upper frequency limit is 66 Hz during the transient based on the allowed value obtained from R.G.1.9, Rev.1, Section C.5 related to transient frequency response for Page 3 of 7

the di; conn::ction of tha larg:st single lord. Tha 3 cccond acceptanca critsria for recovery to steady state is based on 60% of a 5 second load block time per R.G.1.9, however, the use for a load rejection is not the same in terms of applying this criteria.

.' The criteria was, however, considered to be an acceptable conservative response time for governor speed recovery to the new more restrictive steady state frequency range of 60 i 0.5 Hz following the single largest load rejection test.

4. Surveillance Requirement 4.8.1.1.2.d.4.b requires each EDG t'o be demonstrated l

OPERABLE at least once every 18 months during shutdown by verification that the

! EDG can start on a simulated loss of offsite power. The EDG is required to start and energize the emergency buses with all. permanently connected loads within 10 seconds, energize the auto-connected shutdown loads through the sequencing times, and operate for 2 5 minutes. The EDG is required to maintain a generator steady state voltage of 4160 + 420 volts and steady state frequency of 60 1.2 Hz. The proposed change will limit the steady state frequency range to 60 i 0.5 Hz.

5. Surveillance Requirement 4.8.1.1.2.d.5 requires each EDG to be demonstrated OPERABLE at least once every 18 months during shutdown by verification that on an ESF actuation test signal the EDG starts on an auto start signal and operates for > 5  !

minutes. On the automatic start signal, the EDG voltage and frequency limits are 4160 420 volts and 60 1.2 Hz. The proposed change adds the 10 seconds start requirements for voltage and frequency. The voltage is required to be 2 3960 volts and the frequency is 2 59.5 Hz. The change also establishes steady state voltage and frequency of 4160 i 420 volts and 60 0.5 Hz.

6. Surveillance Requirement 4.8.1.1.2.d.6.b requires each EDG to be demonstrated OPERABLE at least once every 18 months during shutdown by verification that the EDG can start on a simulated loss of offsite power in conjunction with an ESF actuation test signal. The EDG is required to start and energize the emergency buses with all permanently connected loads within 10 seconds, energize the auto-connected shutdown loads through the sequencing time, and operate for 2 5 minutes. The EDG is also required to maintain a generator steady state voltage of 4160 420 volts and

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stsady etita frequ;ncy of 60 i 1.2 Hz. Th3 propos;d chango will limit the steady stato frequency range to 60 0.5 Hz.

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' 7. Surveillance Requirement 4.8.1.1.2.d.11.b requires each EDG to be demonstrated l

OPERABLE at least once every 18 months during shutdown by verification that the EDG can restart after it has operated for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or until operating temperatures have

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stabilized. The start and acceleration to at least 900 rpm is required within 10 seconds, and the voltage and frequency requirements are specified as 4160 420 volts and 60 l 1.2 Hz. The proposed change modifies the 10 seconds start requirements for voltage and frequency. The EDG is required to achieve a voltage 23960 volts and a frequency

, 2 59.5 Hz within 10 seconds and achieve a steady state vo'tage and frequency of 4160 i 420 volts and 60 i 0.5 Hz. The reference to the 900 rpm is being removed since it is synonymous to the frequency requirement.

8. Surveillance Requirement 4.8.1.1.2.e requires both EDGs to be demonstrated OPERABLE at least once every 10 years or after any modifications which could affect EDG interdependence by starting both EDGs simultaneously during shutdown. Each EDG is required to start and accelerate to at least 900 rpm within 10 seconds. The proposed change removes the 900 rpm requirement and replaces it with the criteria of achieving a voltage 2 3960 volts and a frequency 2 59.5 Hz within 10 seconds.

Safety Significance Virginia Electric and Power Company has reviewed the proposed Technical Specification changes against the requirements of 10 CFR 50.92 and has determined that the proposed changes would not pose a significant hazards consideration. Specifically, operation of the North Anna Power Station in accordance with the proposed Technical Specifications q j changes will not:

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l 1. Involva c significant incrzse in tha probability or cons:qu:;nc:;s of cn cecident i

j previously evaluated.

l The proposed change provides a more stringent requirement for the EDG frequency i limit at steady state operation of 60 20.5 Hz from the current 6011.2 Hz. The change to the EDG frequency limit does not result in operation that will increase the  !

l probability of initiating an analyzed event and does not alter assumptions relative to  !

mitigation of an accident or transient event. The change to the frequency limit is l

acceptable because the safety analyses assumptions for emergency power limits the frequency variations to 6010.5 Hz and assumes that the EDG supplies the emergency bus with electrical power within 10 seconds of receiving an emergency start signal. The EDG output breaker will close with no electrical power applied to '

the emergency bus when the EDG output reaches 95% of rated voltage. The minimum frequency requirement of 59.5 Hz is based on the steady state limit for the EDG. The EDG supplies the electrical power for the required equipment to mitigate the consequences of design basis events. The minimum voltage and frequency (3740 volts and 59.5 Hz) limits ensure thst the ESF pumps will supply the minimum flow necessary to maintain the fuel within the required parameters to prevent degradation. Therefore, this change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Create the possibility of a new or different kind of accident from any accident previously evaluated.

The proposed change provides a more stringent requirement for thr, EDG frequency at steady state operation of 6010.5 Hz from the current 6011.2 Hz. The change does not introduce a new mode of plant operation and does not involve physical modification to the plant. The proposed change does impose different requirements.

However, these changes are consistent with the assumptions in the safety analyses.

Thus, this change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

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3. Involva a significant reduction n a margin of safety.

The proposed change provides a more stringent requirement for the DG frequency at steady state operation of 6010.5 Hz from the current 6011.2 Hz. The change to I the frequency limit is acceptable because the safety analyses assumptions for emergency power limits the frequency variations to 6010.5_Hz and assumes that the EDG supplies the emergency bus with electrical power within 10 seconds of receiving an emergency start signal. The EDG output breaker will close with no electrical power applied to the emergency bus when the EDG output reaches 95%

of rated voltage. The minimum frequency requirement of 59.5 Hz is based on the steady state limit for the EDG. The EDG supplies the electrical power for the required equipment to mitigate the consequences of design basis events. The minimum voltage and frequency (3740 volts and 59.5 Hz) limits ensure that the ESF pumps will supply the minimum flow necessary to maintain the fuel within the required parameters and meet the accident analysis acceptance criteria. The margin of safety is established through the design of the plant structures, systems and components, the parameters within which the plant is operated, and the establishment of the setpoints for the actuation of equipment relied upon to respond to an event. The change, due to the short time period allowed in this condition, does not significantly impact the performance of structures; systems or components relied upon for accident mitigation or any safety analysis assumptions. Therefore, the change does not involve a significant reduction in a margin of safety.

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